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Anaeróbios

Clostridium perfringens

Large, straight Gram-positive bacilli, spores rarely seen

Identification & Growth

Identification

  • Double zone of hemolysis on blood agar, lecithinase-positive (Nagler reaction), non-motile

Growth Conditions

  • Anaerobic incubation, 35–37 °C; rapid growth, 18–24 h

Clinical Significance

  • Gas gangrene, anaerobic cellulitis, food poisoning, hemolytic bacteremia

Intrinsic Resistance

  • Resistant to aztreonam and aminoglycosides

Bench Alerts

  • A large Gram-positive bacillus with double hemolysis from a wound is a surgical emergency — notify immediately
  • Penicillin plus clindamycin is the classic regimen

Clinical Notes

Clinical presentations

  • Clostridial myonecrosis (gas gangrene): pain out of proportion, crepitus, serosanguineous exudate and rapidly progressive shock.
  • Foodborne illness with watery diarrhoea and cramps 8–16 h after ingestion, usually afebrile and self-limited.
  • Necrotizing enteritis and bacteremia with massive haemolysis, the latter carrying very high lethality.

Specimens and collection

  • Deep tissue from surgical debridement is the best specimen in myonecrosis; send in anaerobic transport.
  • Aerobic and anaerobic blood cultures in every suspected systemic case.
  • In foodborne outbreaks, diagnosis relies on enterotoxin detection or high spore counts in stool, not on culture alone.

Epidemiology and at-risk populations

  • Present in soil, water and the intestines of humans and animals; spores survive cooking and germinate during slow cooling.
  • Myonecrosis follows contaminated trauma, crush injury, bowel surgery and septic abortion.
  • It is a leading cause of foodborne illness in large-batch prepared meals.

Resistance and therapeutic implications

  • High-dose penicillin plus clindamycin is the classic regimen: clindamycin reduces toxin production.
  • Intrinsic resistance to aminoglycosides, aztreonam and trimethoprim-sulfamethoxazole — do not report these as options.
  • Early, extensive surgical debridement is the decisive prognostic factor; antimicrobials are adjunctive.

Bench and reporting notes

  • Large, boxcar-shaped Gram-positive rod, without visible spores in clinical material, and non-motile — a characteristic combination.
  • Double zone of haemolysis on blood agar and a positive Nagler reaction (lecithinase) support presumptive identification.
  • A result suggesting myonecrosis is critical: telephone the clinician immediately and document the communication.

Sources

Educational decision-support content. It does not replace laboratory validation, current guidelines or review by the responsible professional.

FAQ: Frequently Asked Questions

How to identify Clostridium perfringens in the lab?

Clostridium perfringens is identified through double zone of hemolysis on blood agar, lecithinase-positive (nagler reaction), non-motile.

What are the intrinsic resistances of Clostridium perfringens?

This organism is naturally resistant to resistant to aztreonam and aminoglycosides. These drugs should not be reported as susceptible.

Where is Clostridium perfringens commonly found?

It is typically associated with gas gangrene, anaerobic cellulitis, food poisoning, hemolytic bacteremia.

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